Method for vibration damping of workpiece transport device driven elements

ABSTRACT

A method serves to actively perform vibration damping of driven elements of workpiece transport devices in and on shaping machines, especially presses and punches. A measured state value of the driven element or one reconstructed by an observer is determined. The state value is then entered into a damping regulator which affects the drive of the driven elements. A damping regulating circuit is provided in addition to a position regulating circuit.

This is a divisional of application Ser. No. 08/505,536, filed Jul. 21,1995, now U.S. Pat. No. 5,692,736.

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates to a method for vibration damping ofdriven elements of workpiece transport devices in and on shapingmachines, particularly presses and punches.

The mechanical parts of electrically driven elements of workpiecetransport devices in and on shaping machines, especially presses andpunches, must be as rigid and vibration-damping as possible because ofthe acceleration forces that develop, the weight of the elements, thevibrational excitations caused by the drives of the elements, and thevibration of the press.

Because of these requirements, the mechanical elements are usuallycumbersome and expensive. For example, in order to keep the masses to bemoved low, fiber-bonded materials are used to achieve the desiredstiffness of the mechanical elements.

To achieve this goal, mechanical damping devices are known in practice.Thus, for example, DE-PS 30 04 862 discloses a transfer device fortransporting workpieces from station to station on a press, which has abraking device that counteracts the rotational movement of a shaft.

German Patent 22 00 754 discloses a drive for gripper rail lengthwisemovement on mechanical presses, especially transfer presses, in whichthe individual masses of the components to be moved as well as thedistances to be traveled are kept as low as possible. Thus, even when itis used on presses with a high number of strokes, for example high-speedtransfer presses, quiet, low-vibration operation with low wear of thetransmission elements is sought to be achieved.

However, a disadvantage of the above-mentioned approaches for achievingthe goal is that the devices are complex and hence expensive tomanufacture and install.

The present invention therefore has as its object a method for vibrationdamping of driven elements of workpiece transport devices in and onshaping machines, which is both economical and simple.

According to the present invention, this has been achieved by providingthat the vibration damping is performed actively, with a measured statevalue of the driven component or one reconstructed by means of anobserver is determined, with the state value being entered into adamping regulator, which regulator acts on drive of the driven elements,with a damping regulating circuit being provided in addition to aposition regulating circuit.

By providing active vibration damping that is implemented by a dampingregulating circuit in addition to a position regulating circuit, complexmechanical devices can be completely eliminated since the vibrationdamping is accomplished by directly influencing the drive of the drivencomponents.

To determine the movement of the center of the transfer rails that canoccur, for example, during vibration, a state value or characterizingvalue of the driven element is determined directly or indirectly. Thisvalue is fed into the damping regulator and used as a measured value forthe damping regulation and is evaluated by the latter.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects, features and advantages of the presentinvention will become more apparent from the following detaileddescription thereof when taken in conjunction with the accompanyingdrawings wherein:

FIG. 1 is a schematic circuit diagram of a first embodiment of thepresent invention;

FIG. 2 is a schematic circuit diagram of a second embodiment of thepresent invention;

FIG. 3 is a schematic circuit diagram of a third embodiment of thepresent invention; and

FIG. 4 is a schematic circuit diagram of a fourth embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE DRAWINGS

An electrical drive 1 with position regulation, with direct and/orindirect position determination, drives, for example, a transfer rail ina press system, with the transfer rail being capable of vibratingbecause of its movements. The behavior of the transfer rail as itvibrates is shown schematically in FIG. 1 by reference numeral 2. Drive1 moves the transfer rail into a drive position x_(A), but because ofthe vibrations that occur, the center of the transfer rail is not inposition x_(A), but in a different position x_(TS).

The state values of the transfer rail, i.e., for example, theacceleration of the transfer rail, are read into an observer 4.

The goal of observer 4 is to calculate the characterizing values of asystem that cannot be measured directly or are not measured, in otherwords state values 3. By using observer 4, for example, the use ofcostly sensors can be eliminated. A regulation-engineering model of thesystem to be observed, in this case the transfer rail, is used inobserver 4.

At the same time, the set or actual value of drive speed 5 of drive 1 isread into observer 4. From these state values 3 as well as the set valueor actual value of drive speed 5, the observer 4 determines orimplements an observed speed 6 of the middle of the transfer rail. Theobserved speed 6 is entered into a damping regulator 7, with the guidespeed 8 also being entered as an additional input value, as indicated bythe dashed line in FIG. 1.

Guide speed 8 is the speed that serves as the basis for determining aposition guidance value 9. Guide speed 8 is based on the programmed lawof motion for the workpiece transport device, and the time or guideangle therefor. Damping regulator 7 calculates the required values fordamping the vibration of the transfer rail. The value determined bydamping regulator 7 then influences drive 1.

In addition, position guidance parameter 9 is provided as an input valuefor drive 1. Position guidance value 9 represents the position set pointfor each of the three (for example) axes of the transfer rail. Theposition check point of each axis is determined from the programmed lawof motion of the programmed starting and end positions of the transferrail as well as the time or a guide angle.

In the embodiment according to FIG. 1, therefore, the observed speed 6of the middle of the transfer rail is fed back into damping regulator 7,which influences drive 1, so that active vibration damping is provided.Damping regulator 7 is configured, for example, as a proportionalregulator.

The second embodiment of the present invention shown in FIG. 2 uses thesame reference numerals already used in connection with FIG. 1 todescribe the same elements. In contrast to the embodiment in FIG. 1,however, an observer 4 is not used, i.e. the measured state values 3 areread into a device 10 for determining the speed of the middle of thetransfer rail.

Device 10 for determining the speed of the middle of the transfer railhas as its direct output value the speed 11 of the middle of thetransfer rail that is read into damping regulator 7. The guide speed 8can also be entered into damping regulator 7. Position guiding value 9as well as the value determined in damping regulator 7 are also enteredfor drive 1, which is likewise made in the form of a drive with positionregulation using direct and/or indirect position determination. As aresult, damping regulator 7 influences drive 1, so that the vibrationsof the transfer rail are damped.

In contrast to the embodiment in FIG. 1, in which the observed speed ofthe middle of the transfer rail is fed back to damping regulator 7, theembodiment shown in FIG. 2 feeds back the speed of the middle of thetransfer rail, which is determined in device 10 for determining thespeed of the middle of the transfer rail without using an observer, intodamping regulator 7. In the embodiments of both FIGS. 1 and 2 thedamping regulating circuit is superimposed on the position regulatingcircuit.

FIG. 3 shows a third embodiment in which an electrical drive 12 withspeed regulation is operated at a drive speed v_(A). Because of drivespeed v_(A), a transfer rail 20 can vibrate. In contrast to theembodiments in FIGS. 1 and 2, the speed of the transfer rail is used asstate value 3 in the embodiment of FIG. 3 where the position of themiddle of the transfer rail is characterized by the symbol x_(TS).

State values 3 are measured on transfer rail 20, from which values theacceleration of the middle of the transfer rail is determined in adevice 13. The value 14 of the determined acceleration of the middle ofthe transfer rail is entered in damping regulator 7, and the guidanceacceleration 18 can also be entered into damping regulator 7. Inaddition to damping regulator 7, a position regulator 15 is provided inthe present embodiment, in which the position x_(TS) of the middle ofthe transfer rail as well as guide value 9 are entered.

In position regulator 15, from the measured actual position of thetransfer rail and the determined position guidance value 9, a componentof the speed set point for transfer rail 2 is determined, i.e. arotational speed set point for drive 12 is determined, which is thenpassed on to a device 16. The output values of both position regulator15 and damping regulator 7 are combined in device 16 for the speed setpoint that influences drive 12 of transfer rail 2. As a result thevibrations of transfer rail 2 are actively damped.

In the embodiment of FIG. 3, the position regulating circuit issuperimposed on the damping regulating circuit. Alternatively, however,provision can be made such that the damping regulating circuit issuperimposed on the position regulating circuit.

FIG. 4 shows another embodiment similar to that of FIG. 3 but, insteadof device 13 for determining the acceleration of the middle of thetransfer rail, an observer 4 can be used to determine the observedacceleration 19 of the middle of the transfer rail and then to pass thisvalue to damping regulator 7.

Provision is also made in the embodiment of FIG. 4 such that the setvalue or actual value 17 of the drive speed of drive 12 is entered intoobserver 4 for the acceleration of the middle of the transfer rail. Inaddition, the guide speed 18 can be read into.damping regulator 7. Theremaining configuration and function of the embodiment shown in FIG. 4otherwise substantially correspond to the embodiment of FIG. 3.

The entire regulating system, as described in the embodiments of FIGS. 1to 4, can be built in a microcomputer or microprocessor, with thevibrational behavior of the transfer rail being described by asecond-order differential equation. The microprocessor or microcomputercan be part of a numerical control or a drive amplifier, or thefunctions can be distributed over both systems, each of which has amicrocomputer.

Although the invention has been described and illustrated in detail, itis to be clearly understood that the same is by way of illustration andexample, and is not to be taken by way of limitation. The spirit andscope of the present invention are to be limited only by the terms ofthe appended claims.

What is claimed is:
 1. A method for actively performing vibrationdamping of vibrations induced in driven elements of a workpiecetransport device in a shaping machine, comprising the steps ofdetermining in a shaping machine measured state values of the drivenelements, entering the state values into a damping regulator operativelyassociated with a position regulating circuit and a damping regulatorcircuit to directly control drive of the driven elements in multipleaxes of motion of the driven elements, using additional state values todetermine the first-mentioned state values and thereby dampen vibrationsin the driven elements.
 2. The method according to claim 1, wherein thedamping regulating circuit is superimposed on the position regulatingcircuit.
 3. The method according to claim 1, wherein the positionregulating circuit is superimposed on the damping regulating circuit. 4.The method according to claim 1, wherein one of guide speed and guideacceleration of the driven elements is entered into the dampingregulator as an additional input value.
 5. The method according to claim4, wherein the damping regulating circuit is superimposed on theposition regulating circuit.
 6. The method according to claim 4, whereinthe position regulating circuit is superimposed on the dampingregulating circuit.